1. Field of the Invention
The present invention relates to an electrostatic-capacitance-type coordinate input device used as a pointing device for a personal computer and, more particularly, to a thin input device.
2. Description of the Related Art
FIG. 11 is a sectional view showing a conventional input device in a simplified manner. This input device 100 is of a pad type, which is one type of pointing device incorporated in a notebook personal computer.
In this input device 100 shown in FIG. 11, an X electrode layer 103 formed of a plurality of X electrodes 102 is multilayered on the top surface of a film substrate 101 made of a synthetic resin, and a Y electrode layer 105 formed of a plurality of Y electrodes 104 is multilayered on the underside of the film substrate 101. The X electrode 102 and the Y electrode 104 are arranged in a lattice form.
The surfaces of the X electrode layer 103 and the Y electrode layer 105 are coated with insulating films 106 and 107, respectively. Next, a surface sheet 108 is disposed on the X electrode layer 103 side, which is the operation surface side. All the outer dimensions of the electrode layers 103 and 105, the insulating films 106 and 107, and the surface sheet 108 are formed as the same rectangle.
Furthermore, a control circuit substrate 110 is disposed in the bottommost layer on a side opposite to the surface sheet 108, and a control circuit 111 is disposed on a surface opposite to the film substrate 101. The control circuit substrate 110 is also formed with outer dimensions which are the same as those of the film substrate 101.
Furthermore, in the input device 100, through holes (not shown) are formed in the film substrate 101, the insulating film 107, and the control circuit substrate 110. The X electrode layer 103 and the Y electrode layer 105 are made to electrically conduct with each other, so that a signal based on the electrostatic capacitance detected by the X electrode layer 103 and the Y electrode layer 105 is sent to the control circuit 111.
However, in the above-described conventional input device 100, since all the electrode layers 103 and 105 including the film substrate 101 are provided on the control circuit substrate 110, the thickness dimensions of the entire input device become large, and when the input device 100 is incorporated in a notebook personal computer (PC), the thickness dimensions of the PC cannot be made thinner. Furthermore, since the control circuit substrate 110 becomes the same size (area) as that of the film substrate 101, costs are increased.
In order to mount the input device 100 on a PC housing, etc., a support plate made of metal is mounted on the input device 100, and the support plate is screwed in to the PC housing. Furthermore, a rectangular opening for the input device 100 is formed in the PC housing, for example, in front of the keyboard, so that the input device is exposed from the surface of the PC housing, and the input device is provided in the opening.
When installing in the PC housing, a support plate and an opening are necessary, costs are increased, and the flexibility of design of the PC housing is decreased due to the formation of the opening.